HYDRAULIC TRANSMISSION DEVICE FOR VEHICLE

摘要

PURPOSE:To effectively cool an engine as much as possible even in the case where steering is carried out frequently. CONSTITUTION:A hydraulic transmission device is equipped with a cooling fan device 24 installed in a feeding passage 18 for feeding the working oil having the higher pressure than that of a feeding source 34 and a power steering device 20 which is installed between the feeding passage and a return passage 14 for returning the working oil into the feeding source. The cooling fan device is equipped with a hydraulic motor 38 for revolving the fan, passage 40 making a detour around the hydraulic motor, and a differential pressure control valve 47 installed in the passage. The differential pressure control valve is controlled so that the differential pressure between before and behind the hydraulic motor becomes the difference Pp-Ps between the pressure Pp of the working oil supplied from the feeding source and the pressure Ps on the upstream side from the power steering device.